Loudspeaker and like instrument



1936- R. R. GLEN 2,049,766

LOUDSPEAKER AND LIKE INSTRUMENT Filed March 27, 1955 A 5 1/ 10 02/15 2 E A; 9

l i 7 6 1 l E 3 4 INVENTOR QWW MW MM MW Patented Aug. 4, 1936 UNITED STATES PATENT OFFICE LOUDSPEAKER AND LIKE INSTRUIVIENT Application March 27, 1935, Serial No. 13,240

In Great Britain July 4, 1934 4 Claims.

This invention relates to improvements in loudspeakers and like instruments (for example, horns or hooters) and has for its object generally to improve the tone quality and fidelity of reproduction of such instruments.

More particularly, the invention relates to loudspeakers or like instruments of the type having a vibrating diaphragm or sound cone, and has for its object 'to provide, in combination with a main sound cone, a second or sound modifying cone supported in an inverted position with respect to the main sound cone and out of direct contact therewith.

Another object of the invention is to provide a loudspeaker or like instrument of the type referred to in which the position of the inverted cone which may be the smaller of the two, is made adjustable with respect to the main sound cone. According to another feature of the invention, such smaller cone is made open at its smaller and outer end.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. l is a view showing a cross section of a loudspeaker, taken on the line I-l in Fig. 2, constructed in accordance with the invention;

Fig. 2 is an elevational view looking into the mouth of the loudspeaker shown in Fig. 1; and

Fig. 3 is an enlarged fragmentary view of the apex of the smaller cone showing the associated fixing means.

Referring now to the drawing, and particularly to Fig. 1, a main loudspeaker is shown at l,

which is actuated by any suitable driving means, for example, by a spaced driving cone I0 having an electromagnetic driving unit I l as set forth in my copending case, Serial No. 748,474, filed October 16, 1934. The main sound cone I has supported coaxially within it, with its smaller end outermost, a sound modifying cone 2 which is shown as smaller than cone I and is attached by an axial metal tube 3 to an axial threaded rod 4 which engages with the nut portion of a spider or cross frame 5 carried across the mouth of the larger cone. The rod 4 is provided atits outer end with a handwheel 6 whereby the rod may be screwed into or out of the frame and the axial position of the inner cone adjusted relative to the cone I. To provide the desired sound modi- 5 fying effect, the smaller cone is preferably cut to make a circular hole 1 at its apex that forms an annular opening about the metal tube 3 which is connected to the edges of this hole by suitable means, for example, by splitting the tube into 10 three symmetrically disposed strips 8 which are splayed outwardly and affixed to the wall of the smaller cone. The central hole in the smaller cone is thus open except for the three strips aforesaid. 15

A stop 9 is provided on the rod 4 so that the smaller cone is always supported in such manner that there is an annular space between its periphery and the wall of the larger cone. The sound emerges through this space and through 20 the central hole I in the smaller cone and by adjustment of the position of the inner cone through movement of the wheel 6 the quality and fidelity of the sound emitted may be adjusted to suit individual tastes. 2

In an advantageous embodiment, a loudspeaker of the present invention has sound cones of relatively wide angles, for example, the angle of each cone may be In other dimensions, such embodiment is preferably not too bulky, for example, the diameter at the mouth of the main cone may be about 14 inches while the smaller cone is about 5% inches; the diameter of the smaller open end of the smaller cone may be about inch. The maximum axial adjust- 35 ment of the smaller cone in such case is about 1% inches and the stop 9 is arranged so that the minimum perpendicular distance between the edge of the smaller cone and the surface of the larger cone is about A, inch. I

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or 45 shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent 5 is:

1. In loudspeakers and like instruments, the combination with a main sound reproducing cone, of driving means for causing said main cone to reproduce a desired acoustic effect, a 55 second sound modifying cone having a central supporting mounting and free edge, said second cone being disposed in mutually inverted relation to said main cone, and means for adjusting said mounting whereby said second cone is adjusted with respect to said main cone.

2. In loudspeakers and like instruments, the combination with a main sound reproducing cone, of driving means for causing said main cone to reproduce a desired acoustic eifect, a second cone of smaller diameter than said main cone and having a central supporting mounting and free edge, said second cone being disposed coaxially in mutually inverted relation to said main cone, and means for adjusting said mounting whereby said second cone is adjusted axially toward and away from said main cone.

3. In loudspeakers and like instruments, the combination with a main sound reproducing cone, of driving means for causing said main cone to reproduce a desired acoustic effect, a second cone cut to provide an opening at its apex, a supporting tube secured to said second cone and disposed in said opening but spaced from the edges thereof whereby an annular space permitting the emergence of sound is provided, and adjusting means engaging with said tube and with a support secured to said main cone.

4. In loudspeakers and like instruments, the combination with a main sound reproducing cone, of driving means for causing said main cone to reproduce a desired acoustic eflect, a common support for said main cone and driving means, a spider secured on said support, a second cone disposed between said spider and said main cone and mutually inverted with respect to the same, said second cone being smaller in diameter than said main cone and arranged to be coaxial therewith and having its apex cut to provide a central opening, a supporting tube of less diameter than said opening having an end split to provide splayed portions secured to said second cone at points adjacent said opening, and an adjusting screw in threaded engagement with said spider arranged to support and move said supporting tube.

ROBERT R. GLEN. 

